1. Field of the Invention
The present invention relates to a method for suppressing mycotic infection in garlic, and, more particularly, to a cross defense method for suppressing mycotic infection in garlic such as garlic dry-rot, and to microorganisms used for said cross defense method.
2. Description of the Background Art
In the modern agriculture, the excessive pursuit of profit has expelled its long cherished crop rotation system and forced the agricultural system into repeated cultivation or exclusive cultivation of the same crop on the same ground. In addition, the repeated use of abundant chemical fertilizers, soil improvers and herbicides for maintaining this crop system eventually lead to the outbreak of unforeseeable soil diseases in many crop fields. A major cause of the diseases is considered to be the increase in the population of pathogens in the soil. Although various germicides have been used as a countermeasure to this problem, they sometimes worked adversely to kill even useful microorganisms so that they worsen the soil conditions than ever and not necessarily deemed as an effective measure. Risks to the environment caused by the abundant use of chemicals, including germicides or the like, are also pointed out.
Under these circumstances, interest in the biological fungicides, that are microorganisms which suppress harmful creatures, is increasing. This kind of suppressing measure, which involves cross defense mechanism, is advantageous in that it attacks only specific creatures and not contaminates the surrounding environment. Among a number of researches on biological fungicides in the past, there is a report that the use of a non-pathogenic strain of Fusarium oxysporum isolated from the roots of sweet potato was dramatically effective for suppressing the stem-rot of sweet potatoes (Ogawa et al. Syokubutsu boueki, vol.38, No.12, pp.535-538, 1984). Regrettably, the suppressing effect is strictly specific to a certain specie and not directly applicable to other species of plants.
Referring to the diseases of garlic, on the other hand, garlic dry-rot and the like are known as diseases caused by mycotic infection and a method for exterminating these diseases has been earnestly desired.
The present invention is, therefore, directed to the provision of a novel microorganism effective in the suppression of mycotic infection in garlic and to a method for exterminating the diseases in garlic by the use of such a microorganism.
In view of this situation, the inventors of the present invention have conducted extensive studies, and as a result, have succeeded in the isolation of novel fungi from a healthy bulb of a garlic or the rhizosphere of garlic roots and found that the fungi possessed a cross defense ability against mycotic infection in garlic. This finding has led to the completion of the present invention.